Is green your colour?

21 May, 2010
The incentives for bakers to become more energy-efficient are all there, but what equipment options do you have? Anne Bruce takes a look
Page 34 

By its very nature, baking is an inefficient use of energy: baking requires the highest temperatures (200-240°C); bread is a low-density product (90% air); and the occupation ratio in an oven is generally very small.

Then there is the energy required for the preheating of the oven, as well as extra energy for the steaming that occurs at the beginning of the baking process. So in these days of environmental awareness, it may be lucky that baking has not been banned.

That said, the Carbon Trust does have the baking industry firmly in its sights, with the aim of improving its carbon footprint and with grants on offer to those who make green choices. Also, the impact of rising energy costs on bakery firms is a strong incentive for bakers to look at reducing their carbon footprint.

Unfortunately, the additional environmental considerations don't make the already difficult and confusing choice of a new oven any easier. So what technologies are being developed, what is on the market from some of the key suppliers, and what funding is available from the Carbon Trust?

Well, to start with the funding, the Carbon Trust offers loans of up to £100,000 in mainland Great Britain and £500,000 in Northern Ireland to bakers who wish to invest in energy-efficient ovens. The interest rate is 0%, with energy savings offsetting repayment costs. The scheme is available to any baker who can save six tonnes of CO2 emissions a year and an inspector from the Carbon Trust will visit the premises and verify this. A spokeswoman for the Carbon Trust says bakers can apply direct to the scheme, or through their oven supplier if the supplier has arrangements in place. Demand from the baking industry is currently high, she adds.

Some of the options available include the Trezzaforni Steam Tube Oven from Italy, sold through Interbake in the UK. The two-, three- or four-deck ovens run on wood pellets that are produced from compressed sawdust a by-product of the forestry industry. Because the tree, while reaching maturity, absorbs carbon from the atmosphere, the wood pellets are termed as zero-carbon.

The energy produced from the wood pellet burner is 66% cheaper than gas on today's prices. With future price increases predicted on gas, using this type of wood pellet oven can potentially save thousands of pounds in running costs, says Interbake MD David Dunne.

The benefits of baking with this type of unit are solid refractory materials, which provide a very mellow bake characteristic that is radiated throughout the baking chambers by means of steam tubes. These transmit a uniform heat throughout each baking chamber. This method of baking is very traditional, and is associated with baking on falling heat. Carbon Trust loans are available on this product through Interbake.

Lower electrical power

A steel band travelling oven that is claimed to consume up to 45% less electrical power than rival systems is being hailed by its Danish maker as a major step forward in convection oven technology. Supplied by Epsom-based European Process Plant, the modular oven, called the Conny, is manufactured by Aasted Danish Food Technology. The oven, can be gas- or oil-fired, and features a heat transfer system, based on a balanced air velocity in the heat exchanger. When heated, air is distributed to the top and bottom ducts, the airways of which have been aerodynamically designed to ensure the most efficient airflow, maximum heat transfer and minimum heat loss.

The oven's impressive energy consumption figures are enhanced by its energy recovery system, called RecConny. Heat recovery rates up to 80% have been achieved using the system, which results in energy savings and considerably lower CO2 emissions. RecConny can be retrofitted on most convection ovens, says the firm.

Also supplied by EPP is the MIWE eco:nova heat recovery system. Stewart Morris, EPP director, says: "Energy costs have soared in recent years and MIWE has responded to this by designing a highly effective heat recovery system, specifically designed to operate at its optimum in the conditions found in bakeries." In most cases, the typical savings in a single day can be about 600 kilowatt hours. This, however, depends on how much energy is consumed during baking and the savings can vary from product to product. For example, the savings from crusty rolls are far greater than for croissants.

The MIWE eco:nova is best-suited for bakers with more than four ovens and a gross burner capacity of at least 320kW. There are almost no upwards boundaries. The MIWE eco:nova can be constructed in modular steps, of 160kW (burner capacity).

Brook Food Processing Equipment can also source Carbon Trust funding for customers on new Polin ovens when they are replacing their old, less energy-efficient ovens. The Polin oven range covers small bake-off ovens, modular deck ovens, rack ovens and steam tube artisan ovens.

The loans can include the costs of changing electrical supplies, the removal of old equipment, installation of the new equipment and can be offered on a five-year agreement. A spokeswoman says: "We have worked alongside 'cost of life' consultants to calculate emissions, energy usage and running costs and, in most cases as we are yet to find an exception, we are able to offer a more efficient new Polin oven against the existing oven."

Hamburg-based Daub handled in this country by Benier UK offers a thermal oil heating system, boasting reduced energy costs. The thermal oil is heated in a heat exchanger unit outside the oven and then distributed through a series of radiator plates above and below each shelf in a rack oven. Each oven has its own pump, and precise temperature control is achieved by throttling oil from the primary heat exchanger circuit through the oven circuit.

Once the oil is heated, temperatures do not drop significantly when the oven is loaded or emptied and, as the heat capacity of thermal oil is 2,600 times higher than hot air, baking times are significantly reduced.

Den Boer, based in the Netherlands, offers Multibake industrial tunnel ovens, used for products including bread, pizza, puff pastry and pies. The company's power consumption management technology means that energy use is measured, controlled and adjusted in detail. Measurement of actual and average gas and electricity consumption in cubic metres per hour and kWh gives an insight into energy-saving potential when adjusting recipes; it also increases the accuracy of product cost calculation. Recognition of peak tariffs means that production can be switched to the cheapest tariff periods.

For smaller operations, supplier Rational's Self-Cooking Center is designed to be environmentally friendly, made with all recyclable materials. During use, the Rational SelfCooking Center, a combi-steamer, uses up to 60% less energy than conventional alternatives, it says, and uses at least 10% less energy than normal combi-steamers. Insulating materials are designed to ensure the heat stays in the cooking cabinet. All components of the SelfCooking Center are optimised for minimum energy consumption. For example, the fan motors are brushless 500W direct current motors, with an efficiency of approximately 95%.

Because the SelfCooking Center has low heat emission into the kitchen area, there is less demand placed on ventilation equipment, such as extractor hoods and air conditioning systems, cutting the energy consumption of such units.


Exploring new technology

While the above lists some of the options on the market at present, buying an oven is a long-term commitment. So what is coming down the line in future? Professor Alain Le Bail is co-ordinator of an EU-funded project that has looked at developing more energy-efficient ovens, EU-Freshbake.
Two of the innovative technologies he examined have actually recently been launched into the UK by supplier Capway Systems UK radio frequency and microwave ovens.
Capway, supplied by the Dutch company Stalam, is targeting the ovens at medium-to-large bakers in this country. The Stalam technology is already being successfully used in Spain.
Different versions of this sort of oven, used in the UK a few years back by one particular plant baker, were not cost-effective, but times have changed. The ovens are particularly suitable for crustless and par-baked products. They offer 60% shorter baking times and 90% improved energy efficiency, according to a spokesman. There is also no need to preheat and 0% carbon dioxide emissions.
Professor Le Bail says other high-tech energy-saving options include impingement ovens, which consist of high-velocity air jets. The heat transfer by forced convection in an impingement oven is high and the technology reduces baking time and moisture loss, as well as using lower oven temperature and having lower operating costs.
Infrared baking technology can also save energy, as the air in the oven is not heated and shorter baking times are achieved.
As part of the EU-Freshbake project, academics at Professor Le Bail's college, ONIRIS (l'Ecole Nationale Vétérinaire, Agroalimentaire et de l'Alimentation Nantes-Atlantique), developed a low-energy baking oven, based on infrared technology.
Results showed that a 35-40% energy saving was obtained. In addition, the pre-heating time was significantly reduced (by 70%).
But bread baking remains largely a "conventional" process and most environmental developments are more concerned with how to mimic the craft baker than on developing high-tech baking systems, says Le Bail. As in most things, however, it's a case of horses for courses.





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